This invention relates to tools for retrieving items from the bottom of a well bore, and, more particularly, to tools for bringing the retrieved item back to the surface from the bottom of the well bore.
Typical prior art tools for bringing to the surface items retrieved from the bottom of a well bore are disclosed in the following U.S. Pat. Nos. 2,493,992; 2,520,783; and 3,203,491. These prior art tools, however, have various limitations. For example, the tools disclosed in U.S. Pat. No. 2,493,992 can be actuated only once before withdrawing the entire fishing string. The embodiment shown in FIGS. 1 and 2 includes a junk basket arrangement that is closed by mechanical actuation of the tool, while the basket shown in FIG. 3 is actuated by use of an electromagnet. In each case, however, once the basket is closed, it is apparent that the basket cannot be re-opened without withdrawing the entire fishing string out of the well bore. Thus, it is not possible to lower an electromagnet through the basket, once the basket has been closed. The baskets disclosed in U.S. Pat. Nos. 2,520,783 and 3,203,491 have similar limitations. The basket disclosed in U.S. Pat. No. 2,520,783 is actuated mechanically, while the basket in U.S. Pat No. 3,203,491 is actuated hydraulically. In either case, an electromagnet can not be lowered through the basket once the basket has been closed.
The present invention overcomes the above-noted and other drawbacks of the prior art by providing a remotely operable downhole junk basket system which allows an operator to open and close the basket as often as is desired while it is at the bottom of a well. Expressed otherwise, the basket can be opened more than once down the hole so that an electromagnet can be raised and lowered repeatedly through the basket.
The invention in a general sense comprises an inner tubular member which fits within an outer tubular member in an axially or longitudinally slideable relation. The outer member is adapted to attach to the lower end of a pipe string; it serves as a tubular driver in transmitting axial or torque loadings from the pipe string. The inner tubular member serves as a tubular opener; it provides an opening through which a fish in a well may be retrieved. The lower end of the inner tubular member preferably comprises a bit, a washover shoe, or other tool for engaging the bottom of a well.
A lower internal wall portion of the outer tubular member or tubular driver and an upper external wall portion of the inner tubular member or tubular opener are configured to define one or more annular chambers or cavities to house springs which are compressed upon upward axial movement of the inner tubular member relative to the outer tubular member. The spring or springs thereby urge the inner tubular member downward relative to the outer tubular member when the two members telescope together.
A junk catcher or basket is mounted in the internal wall of the outer tubular member above the spring chamber or cavity. The catcher or basket comprises a cylindrical housing with a plurality of arcuately spaced internal openings to house a corresponding plurality of fingers. Each finger is spring-loaded and pivotally mounted at its lower end in its respective opening to extend radially inward in a lateral, or transverse, position. In their transverse position, the fingers overhang the upper end of the inner tubular member, such that upward movement of the inner tubular member relative to the outer tubular member forces the fingers into their retracted vertical positions within the basket. Preferably, the inner tubular member is provided with sufficient axial travel such that its upper end can slide within the basket with the fingers in their retracted position.
Releasable interlocking means may be employed to hold the inner and outer tubular members telescoped together with the basket fingers in their retracted vertical position. A preferred such means is a shear pin which may be sheared by bumping the inner tubular member against the bottom of the well.
When the two tubular members are telescoped together, a junk retriever such as a hook or an electromagnet may be lowered on a wire line, reelable tubing or the like down through the basket to a piece of junk, a fish, or other object at the bottom of a well. The retrieved object may then be lifted above the retracted fingers. The fingers may then be released to a lateral position to form the bottom of a basket, to hold the retrieved object. If desired, as for example when employing an electromagnet, the basket itself may be used to carry the object to the surface of the earth.